The present invention relates to an anesthetic waste gas evacuation system and in particular an evacuation system for removing anesthetic gases discharged from an anesthesia machine without exposing the patient to a subambient pressure or a state of positive end expiratory pressure.
During normal operation of an anesthesia machine, either in a rebreathing or a non-rebreathing mode, a quantity of the anesthetic gas will be discharged from the machine as waste gas. It is essential that this gas be properly evacuated from the room in which it is being used to the outside ambient atmosphere. It is essential in an evacuation system that there be no vacuum produced at the discharge valve of the anesthesia machine that can interfere with the breathing of the patient.
The evacuation system of the present invention avoids either a subambient pressure or a state of positive end expiratory pressure. This is accomplished by providing a gas collection chamber with the waste gas being introduced into the bottom of the chamber and a small turbine fan at the top of the chamber draws the waste gas and actively pushes the waste gas into an outlet conduit. To avoid a subambient or a state of positive end expiratory pressure within the collection chamber, one or more vents are formed in the collection chamber to provide communication between the chamber and the ambient atmosphere. The net effect of the vents is that the pressure within the chamber will be equal to or very close to the ambient pressure. By allowing the heavier than air waste gas to collect at the bottom of the chamber and drawing this waste gas out through a fan at the top, there is little or no effect on the expiration of the patient.
The gas collection chamber is formed by a metallic housing which is grounded through the electrical power cord. The housing is coupled to a mounting post through an electrically conductive bracket so that the post is also grounded. All other components mounted to the post can be easily grounded by appropriate connection to the post.
Further objects, features and advantages of the invention will become apparent from a consideration of the following description and the appended claims when taken in connection with the accompanying drawings.